I have tested it on my mac, and the onion skin reacts fine here.
I don’t use the 0.6.2 though. Version 0.6.2 has some issues, so we recommend to download the latest nightly build, and use it in stead.
Version 0.6.3 is just around the corner, so the latest nightly build is a de facto Release Candidate for 0.6.3.